Thanks all for the various suggestions. I've now tried my final option which is my trusty Windows 7 net book. The message I get from this when trying to open the zip is that the file is invalid. I can't believe all three computers I have at my disposal are faulty! The option of getting a decent comp...

Not a good start. I got my Rasberry Pi yesterday. I've tried three times to download the Wheezy OS, as recommended by my Rasberry Pi for Dummies ebook. On my home PC (windows 8 ACER) I get a corruped image file notification and my PC at work (window XP lenovo) the file fails download completely! :?...